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151 Cards in this Set
- Front
- Back
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What are nucleons?
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Protons and neutrons together
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When two or more atoms are chemically united, what do they form?
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A molecule
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When an electron is removed from an atom, what does the atom become?
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A positive ion
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When an electron is added to an atom, what does the atom become?
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A negative ion
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What is the atomic mass?
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The number and protons and neutrons in the nucleus
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What is an isotope?
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an atom that has gained or lost neutrons, but the protons in the nucleus remain the same
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Do electrons have mass?
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Yes
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Do photons have mass?
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No
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Define energy.
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The ability to do work
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What is the unit of mass?
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The kilogram = 1000 g = 1000 cubic cm of water at 0 degrees celsius
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What is formed when two or more substances are combined?
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A mixture
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Simple substances are known as _________.
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elements
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Complex substances are known as _________.
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compounds
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How many elements are in the table of elements?
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92 naturally occurring and 18 others
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The ______ is the unit of current.
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The ampere
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______ is the force or electrical pressure that produces electron movement and current flow.
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Voltage
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One ampere is equal to ______.
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One coulomb flowing per second
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True or false. One kilovolt is equal to 1000 volts.
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True
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According to ohm’s law, the current in a circuit with 120 volts and a resistance of 5 ohms is:
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24 ampere
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The unit of power is the watt. One watt is produced by:
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1 ampere flowing with a pressure of one volt.
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Electric power (the watt) is determined by the formula:
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Volts times amperes equals watts.
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If the electricity to your home costs $.75 per kilowatt hour and you operate a 2000 watt vacuum cleaner for 30 minutes, what is your cost for this period of time?
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.75
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Increasing the length of a conductor will also increase:
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resistance
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66 kilovolts carrying 500 amperes will have a resistance of:
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132 ohms
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A semiconductor can be classified as:
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being an insulator and a conductor
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Objects can be electrified by one of three methods: friction, contact, and ________.
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induction
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True or false. If a cicuit is carrying 500 volts and has a resistance of 1 ohm, the amperage in this circuit is 500 A.
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True
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Increasing the temperature in a circuit also increases the:
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resistance
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The greatest concentration of charge in a solid metallic wire will be:
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On the outside surface at an area of sharpest curvature.
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The relationship between current and a changing magnetic field is called:
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Electromagnetic induction
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True or false. It is possible to step-up both the voltage and amperage together with a transformer.
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False, when the voltage is increased, the amperage must decrease
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True or false. Holding a stationary conductor in a stationary electric field will produce a current in that conductor.
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False
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You have a current of 100 volts and 2 amperes on the primary side of your autotransformer. In order to get 10 amperes on the secondary side of your transformer, you must _______ the voltage to ______ volts.
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Stepdown, 20
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A device that converts mechanical energy to electrical energy is called a/an:
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Generator
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Groups of atoms with their magnetic moments or net magnetic field in the same direction are known as:
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Dipoles
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True or false. The input watts on the primary side of a transformer should equal the output watts on the secondary side of that transformer.
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True
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The type of magnet that is produced by heating an alloy within a strong magnetic field is:
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Artificial Permanent
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If a material has high permeability (easily magnetized), it will have ______ retentivity.
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Low
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Which of the following types of materials has high permeability?
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Ferromagnetic
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If the current on the primary side of your step-down transformer is 10,000 volts and the current on the secondary side is 500 volts, how many coils are located in the secondary side if the primary side of the transformer has 100 coils?
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5
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True of false. An autotransformer operates on mutual induction.
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False
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A series of coils of wire within proximity of each other will create a combined magnetic field that can be used as a tool. This device is known as a _______.
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Solenoid
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Rectification of AC current is necessary for:
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Changing the current from AC to DC for devices like x-ray tubes and televisions.
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A device that can take a DC current and turn it on and off several times per second in order to create an AC current is called a/an:
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Inverter
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The type of transformer that can both increase and decrease a voltage in a circuit is known as a/an:
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Autotransformer
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If a transformer has 400 coils on the primary side and 200 coils on the secondary side, this type of transformer is a:
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Step-down transformer
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True or false. Half wave rectification of the power coming into an x-ray machine will utilize only 50% of the incoming power.
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True
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A device that is used in portable x-ray machines that can accumulate and store an electrical charge is a/an:
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Capacitor
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If a transformer has an input of 200 V and 40 amps on the primary side, the output in watts on the secondary side will be:
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8000 Watts
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What is an atom that has one more proton than electrons?
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A positive ion
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Electromagnetic waves are unique in that:
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They don't require a medium to maintain motion and can travel in a vacuum.
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A transformer that is used to step-up 3,000 V to 60,000 V has 4000 coils on the secondary side. How many coils are on the primary side?
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200
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A transformer used to step-down a voltage of 8,000 V to 500 V may have ____coils on the primary side and ____ coils on the secondary side.
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9600, 600
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AC current in the United states flows at a frequency of:
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60 cycles per second
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According to Ohm’s Law, if you multiply the amperage of a circuit by the resistance, your outcome will be the ______.
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Voltage
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Converting AC current to DC current is done with a semiconductor called a:
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Rectifier
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If a radiation has the strength to remove an electron from the orbit of an atom, it is known as:
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Ionizing
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If a transformer has more coils on the secondary side than on the primary side, this is known as a ______ transformer.
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Step-up
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If an atom has 6 electrons and is not a positive ion, then the atomic number of that atom is:
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6
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In an electric motor, we are converting:
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Electrical energy to mechanical energy
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A single-phase half-wave rectified x-ray machine will produce x-rays about:
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50% of the duration of the exposure
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One hertz is equal to _______.
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One cycle per second
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One tesla is equal to ______ gauss.
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10,000
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The amount of protons in a nucleus is equal to the:
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Atomic number
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The energy of electromagnetic radiation is measured in:
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Electron volts (think: keV)
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The formation of a positive ion happens when:
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An electron is removed from the orbit of an atom.
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If the electricity to your home cost you $1.00 per kilowatt hour, the how much would your waterbed cost to run for 24 hours if it used 100 watts per hour?
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$2.40
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The minimum number of electrons that you will find in a K-shell is:
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1 (Hydrogen)
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The maximum number of electrons that you will find in a K-Shell is:
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2
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The most efficient waveform used in diagnostic radiology is:
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High Frequency
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The transformation of radioactive nuclei into a different element is known as:
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Radioactive decay
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The unit of current is the______.
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Ampere
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The unit of electric power is the_____.
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Watt
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To induce an electric current into a stationary conductor, the electromagnetic field must be _______.
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Changing
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Watts divided by voltage equals_____.
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Amperes
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X-rays and gamma rays differ in:
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Origin
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True or false. A binding energy of 69 keV is common with all K-shell electrons of all atoms.
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False
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True or false. According to US Public Law 90-602, generators must terminate the exposure at 600 mAs for exposures above 50 KVP and 2000 mAs for exposures below 50 KVP.
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True
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True or false. Because electrons are heavier than protons or neutrons, they carry a stronger electrical charge.
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False
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True or false. The force between two uncharged particles is attraction.
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False
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What are groups of atoms with a magnetic field in a distinct direction?
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Dipoles
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A single wire with several coils used to combine the magnetic force of an electric current is also known as a:
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Solenoid
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Direct current can be converted into alternating current with the use of:
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Inverters
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What has the least resistance against the flow of electrons?
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Superconductors
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______ is the force or electrical pressure that produces electron movement and current flow.
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Voltage
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The incoming power supply that most all stationary x-ray equipment operates from is:
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210-220 V
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According to ohm’s law, the current in a circuit with 120 volts and a resistance of 6 ohms is:
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20 Amperes
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What is the resistance of a circuit if the voltage is 12 V and the current is 6 amperes?
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2 Ohms
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With a full wave rectified wave form, x-ray production starts and stops:
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120 times per second
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The unit of power is the watt. One watt is produced by:
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1 ampere flowing with a pressure of one volt.
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A P-N junction semiconductor allows current to travel:
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In only one direction in the circuit
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The life expectancy of a tungsten filament is approximately:
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6-9 hours
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Tungsten is the material of choice for filaments because of its high melting point and:
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It is difficult to vaporize
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Because of space charge effect, the maximum mA range achievable with most diagnostic x-ray tubes is:
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1000-1200 mA
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A filament is subject to breaking after _____ of the diameter has vaporized.
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10%
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A grid biased tube is different than conventional x-ray tubes in that:
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The focusing cup can be switched to a positive charge to absorb electrons.
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The type of tube that has the ability to increase the negative charge to the focusing cup in order to reduce the size of the actual focal spot is known as:
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Bias focusing
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How many electrons does a Tungsten atom have?
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74
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What is the atomic number for tungsten?
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74
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What is the Octet rule?
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The maximum number of electrons in the outermost shell cannot exceed eight
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What is the unit of potential difference?
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Volt
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What unit can be described to produce electron movement and current flow?
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Volt
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________ is equal to the product of the current flowing and the resistance of the conductor
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Voltage
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What is the binding energy of an orbiting electron measured in?
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Electron volts
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What is electron binding energy?
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Amount of energy needed to remove the electron from the atom.
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What are the two things that we measure with keV?
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The binding energy of an electron in orbit around a nucleus and the energy of the x-rays we produce.
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How many millimeters are in 1 inch?
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25 millimeters
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How many centimeters are in 1 meter?
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100 (think: century)
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What does a kilo mean?
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1000 (1 kilometer= 1000 meters)
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Why do we need at least 70 kVp to make characteristic x-rays?
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The tungsten atom has a K-shell binding energy of 69.5 keV: this means that we need at least 70 kVp set on the control panel in order to knock this electron from it's orbit and produce a characteristic x-ray.
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What is the transformer law?
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States that the ratio of the Volts to the number of turns on a coil on the primary side will be the same as the ratio of volts to turns of coil on the secondary side. V2/V1=N2/n1
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True or false. An autotransformer can only decrease voltage in a circuit.
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False, increase or decrease
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What is mutual induction?
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Two coils being placed in close proximity w/a varying current supplied to the 1st coil, which then induces a similar flow in the second coil.
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What is self induction?
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When an alternating current (AC) is supplied to a coil, the process by which the current is reversed by the AC also induces a change in the current at another portion of the coil.
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True or false. Autotransformers operate on self induction.
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True
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What operates on DC?
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Continuous source, like a battery (cell phones, etc.)
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True or false. Diodes (solid semiconductors) are most commonly used as rectifiers.
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True, (electrical one way streets, electrons flow one way but not the other. )
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What is inversion?
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Changing DC to AC
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What is created when you add a ferromagnetic core within a solenoid?
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Electromagnet
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What is the inverse square law?
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The intensity of the beam is inversely proportional to the square of the distance from the source. New intensity = old intensity x (d1/d2)squared
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What is the federal law for the inverse square law?
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Federal law states that it cant exceed 100 mR/hr
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What does it mean if something has high permeability?
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It is easy to magnetize
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What does it mean if something has low retentivity?
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it's magnetism is strong, hard to break
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What are dipoles?
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Groups of atoms with net magnetic field, magnetic domains
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What is a single wave rectified waveform?
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a single diode placed within the conductor with an AC current, that current will become a pulsating DC current. Only ½ of incoming current is converted to DC, the other is wasted.
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What is a full wave rectified waveform?
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By placing 4 diodes in a complex circuit you can split and then recombine the current in a full wave rectified waveform. Allows photons to be produced almost 100% of the time.
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What is US public law 90-602?
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Generators must terminate the exposure @ 600 mAs when above 50 kVp and 2000 mAs when below.
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What is a focusing cup made of?
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Nickel, good conductor
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What does a biased focusing cup/tube do?
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Has a more negative charge in order to further focus electrons. Reduces the size of the actual focal spot.
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What is the formula for computing heat units?
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kVp x mAs x rectification number x number of exposures= heat units
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What is a grid biased tube?
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Portable. The focusing cup can be switched to a positive charge to absorb thermionic electrons. This makes it possible to regulate, pulse, or synchronize an exposure.
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What element is added to the tungsten filament and why?
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Thorium is added because it increase efficiency and prolongs the life.
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What is the distance between the cathode and anode?
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1-2 cm
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When were cold cathodes no longer used?
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1915
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Due to the anode heel effect, which side will have less exposure?
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Less exposure on the anode side.
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What is caused by the line focus principle?
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Anode heel effect
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There are 25% ______ photons on anode side and 20% _______ photons on cathode side.
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Fewer, more
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What is the wavelength of x-rays measured in?
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Angstrom is the wavelength of diagnostic x-ray.
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______ speed anodes have higher heating capacities than _______ speed anodes(often 50% greater)
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high, regular
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Wavelength is measured from :
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Crest to crest
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What is an isotope?
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If an atom gains or losses neutrons, the result is an atom called an isotope. Atoms that have the same number of protons in the nucleus but differ in the number of neutrons.
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What element is added to the tungsten target and why?
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Rhenium is added to the tungsten to increase efficiency and conductivity. Rhenium provides greater elasticity when the focal track expands rapidly due to intense heat
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What is different about the tubes used in mammo?
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Uses molybdenum, 42. It’s the primary target material, due to its ability to emit more uniform range of lower energy photons. Lower characteristic energy photons permit a better soft tissue image. The tube uses a beryllium glass envelope because glass in x-ray tubes absorbs too much low energy beam.
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What is the actual focal spot?
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the physical area of focal track that is impacted (focal track- the circular path that will be impacted by electron beam)...controlled by filament size.
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What is the effective focal spot?
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The area of focal spot that is projected out of the tube toward the object being x-rayed. Controlled by the actual focal spot (which is controlled by the length of the filament) and the anode target area.
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What is the line focus principle?
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Permits the best resolution of detail while permitting a large actual focal spot (due to heat). When the target angle is less than 45 degrees, the effective focal spot is smaller than the actual focal spot.
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Why does the anode get hot when an exposure is made?
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Anode serves as a target surface for high voltage electrons from filament. All of these electrons bombard the anode – moving or vibrating atoms at the site-creating heat or thermal energy. These high speed electrons are suddenly stopped (resulting in production of x-ray photon) the anode absorbs that heat.
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What is paramagnetic? and give some examples
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Low permeability. Platinum and aluminum
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What is a three phase generator?
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A combination of 3 full wave rectified circuits that produce 6 or 12 pulses per cycle/hertz that are overlapped (by using a wye or Delta configuration)
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What is a falling load generator?
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Specially designed three-phase or high-frequency generator that begins the exposure at a high mA station and mA decreases as exposure continues. Can do a high mAs without a higher powered generator but tech cannot pick mA and tube gets used up faster.
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Give some examples of elements that are diamagnetic.
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Beryllium, bismuth, lead. Water is also slightly.
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